Minkerd_megold_angol 201

MEDICAL MICROBIOLOGY SHORT ANSWER QUESTIONS
These basic questions will be included in the mid-semester tests (in addition to simple-
choice and multiple-choice questions) and in the written entry test of the Final Examination in
the Department of Medical Microbiology. We would like to emphasize some important
aspects about these questions and answers.
It is important to realize that learning only this material does not give sufficient
knowledge for the tests and examinations. These questions are not to be used to start learning,
rather for measuring your knowledge. However, after a certain amount of learning, students
may use this material for self-testing, and also for identifying dark areas of their knowledge.
The teacher correcting the tests can give 1 point for each answer. As these are basic
questions, only completely good answers will be accepted. However, after careful
consideration, the teacher may give a point for an answer which is 75-80 % good. On the
other hand, if the student writes bad answer(s) in addition to good answers for a question, the
teacher may refuse to give the point, depending on the severity of the mistake.
If you find any mistakes in the questions or answers, or you think that there may be
additional good answers given to a question, please write me, preferably in e-mail (Dr. Veress
György: veregy@med.unideb.hu). We cannot accept any complaints regarding these
Dr. György Veress Associate Professor Academic advisor
____________________________________________________________________ GENERAL MICROBIOLOGY 1.
Describe the colour (in a Gram stained smear) of Gram positive and Gram negative
bacteria, respectively! Gram positives: dark blue/purple Gram negatives: red/pink
Describe the 3 important parts of the bacterial lipopolysaccharide!
lipid A + core polysaccharide + O-specific (polysaccharide) side chain
Which 2 roles are attributed to bacterial pili (fimbriae)?
adhesion; conjugation (sex fimbriae)
Mention a bacterium and its virulence factor that is encoded by a lysogenic
bacteriophage! Corynebacterium diphtheriae – diphtheria toxin Streptococcus pyogenes – erythrogenic toxin
Specify 2 genera containing obligate intracellular pathogens!
Chlamydia, Rickettsia, (Coxiella, Ehrlichia)
Mention at least 5 possible transmission ways of infections!
respiratory droplets (infectious aerosol)faecal-oraldirect contact (such as sexual) fomites (inanimate objects) blood vectors (blood-sucking arthropods)
List the possible shapes of bacteria. Write one example per category.
coccus (spherical): Staphylococcus, Streptococcus rod: Clostridium, Corynebacterium, Gram negative rods curved rod: Vibrio helical: Spirochetes (Treponema, Borrelia, Leptospira)
What are the essential components of bacterial cells? Specify at least 3!
cytoplasm, nucleoid (genome), cell membrane, (cell wall)
Vector is an arthropod that transmits infection from human to human, or from animal to human examples. tick – Lyme disease; louse – epidemic typhus; mosquito – malaria
10. What is a reservoir? Write an example.
The normal host of a pathogen (human or animal) serving as a continuous source of infection to other hosts (such as humans). Salmonella typhi – human; Yersinia pestis - rodents
11. Mention 3 reliable methods of sterilization!
autoclaving, hot air oven, gamma-radiation, filtration (fluids), gas sterilisation (not acceptable: boiling, pasteurisation, UV!) alcohols; aldehydes (alkylating agents); phenol derivatives; detergents; chlorine + iodine = oxidising agents
Mention a group of antimicrobial drugs that act on the bacterial ribosome and usually
has bactericidal effect! aminoglycosides
14. Describe precisely what toxoid means!
Inactivated bacterial exotoxin that is not toxic but immunogenic
15. Mention 2 broad-spectrum (effective against both Gram positive and Gram negative
bacteria) penicillin derivatives. ampicillin, amoxicillin, piperacillin, azlocillin, mezlocillin
16. Mention an antifungal and an antibacterial drug that alter the function of the cell
membrane! antifungal: Amphotericin B, azoles; antibacterial: polymyxins
17. What are the possible mechanisms of acquired penicillin resistance of bacteria? Mention
at least 3 mechanisms! 1. beta-lactamase production 2. PBP (target) alteration3. reduced permeability 4. active efflux
18. Mention a drug belonging to macrolides!
erythromycin, spiramycin, roxithromycin, clarithromycin, azithromycin
19. Mention 2 drugs belonging to aminoglycosides!
streptomycin, gentamycin, tobramycin, amikacin…
20. Mention 2 groups of antimicrobial drugs that act on the 30 S subunit of the bacterial
ribosome! aminoglycosides, tetracyclines
21. Mention 3 groups of antibacterial drugs inhibiting bacterial cell wall synthesis! penicillins, cephalosporins, carbapenems, monobactams, glycopeptides
22. Which part of the bacterial cell carries the endotoxin?
Outer membrane of Gram negative bacteria
23. What role is attributed to the bacterial capsule in the infectious process?
antiphagocytic effect, adhesion
24. Mention 2 infectious diseases that are transmitted to humans by tick bites!
tick-borne encephalitis; Lyme-disease; tularemia; Rocky-Mountain spotted fever; recurrent fever (Borrelia recurrentis) etc.
25. Which type of hypersensitivity is involved in the tuberculin test?
late type (type IV)
26. Mention 2 bacterial infectious diseases that can be prevented or treated by passive
transfer of specific immunoglobulins! prevention: tetanustreatment: diphtheria, botulism, tetanus
27. What do the vaccine(s) against diphtheria and tetanus contain?
Diphtheria and tetanus toxoid
28. What does the vaccine against pertussis contain?
Previously: killed bacteria Currently: acellular vaccine (toxoid + other purified proteins)
29. What does the vaccine against tuberculosis (BCG) contain?
live attenuated Mycobacterium bovis (Bacille Calmette-Guerin)
30. What is the nature of antigen in the vaccines used to prevent infections by
Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis? capsular polysaccharide (either alone or conjugated to a carrier protein)

31. Mention 2 bacterial exotoxins that are neurotoxic! tetanus toxin, botulinum toxin 32.
Specify the 4 groups of bacterial vaccines according to the nature of the antigen! a., live, attenuated vaccines b., killed bacterial vaccines c., toxoid vaccines d., subunit vaccines (capsular polysaccharide or purified protein) 33. What is the mechanism of action of lysozyme? Where is lysozyme found in the host? It destroys bacterial cell wall peptidoglycan by hydrolysing the glycosyl bonds between NAM (N-acetylmuramicacid) and NAG (N-acetylglucosamine). It occurs in tear, saliva, respiratory secretions. 34. Which Gram negative organelles or structures are associated with the O, H and K
antigens, respectively? O- LPS, H-flagella, K-capsule 35. Mention 2 bacterial exotoxins that act by ADP ribosylation! Diphtheria toxin, cholera toxin, pertussis toxin 36. Describe the rules of collecting native urine for culturing bacteria! Describe also the
conditions for keeping the specimen before sending it to the laboratory! A midstream specimen, taken preferably in the morning, after thorough cleaning of the external genital area. Keep it up to 1 h at room temperature or up to 24 h at +4 oC.

37. Describe the rules of collecting hemoculture specimens!
It is recommended to obtain 3 specimens (with at least 30 min. between the specimens). The specimens should be preferably taken before fever spikes (during rising fever), from fresh peripheral venipuncture sites. If possible, both aerobic and anaerobicbottles should be used (3 x 2 bottles altogether). The site of venipuncture and the plug of the bottle containing the medium must be properly disinfected. The amount of blood injected to the bottle should be about 10 % of the liquid medium. 38. Mention two clinical specimens that are heavily contaminated with bacteria belonging
to the normal body flora! throat and nasal secretions, faeces, vaginal secretions. 39. Mention at least three of the physiological effects of septic shock (characterized by the
presence of large amount of bacterial endotoxin in the blood)! fever, hypotension, disseminated intravascular coagulation (DIC), complement activation, impaired organ perfusion, hypoglycaemia 40. What pathogenic role is attributed to lysogenic conversion?
Lysogenic conversion: transfer of genes from one bacterium to another by lysogenic bacteriophages. The bacteria may gain exotoxins (diphtheria toxin, Streptococcus pyogenes erythrogenic toxin), or the structure of LPS epitopes may be altered (Shigella, Salmonella).
41. Describe the principle of acid fast staining procedures!
Mycobacteria contain a high amount of special lipids called mycolic acids. They can be stained by hot carbol-fuchsin, but they resist decolourisation with acid-alcohol, so they remain red. All other cells are stained blue by the counter stain (methylene blue).
42. Mention 2 non-essential bacterial organelles that enhance bacterial virulence! Describe
how their function contributes to pathogenicity! Capsule: antiphagocytic effect, adhesion to tissues Fimbriae: binding to tissues Flagellae: spreading the bacteria

43. Mention a differentiating culture medium and describe which groups of bacteria are
distinguished on the mentioned medium! Eosin-methylene blue (EMB) agar: Inhibits Gram positive bacteria and inhibits the swarming of Proteus. Differentiates between lactose fermenters and non-fermenters. Lactose fermenters produce high amounts of acids, which is indicated as dark blue colonies by eosin and methylene blue. McConkey agar: Inhibits Gram positive bacteria by bile salts and crystal violet. It differentiates between lactose fermenters and non-fermenters. Lactose fermentation is indicated by neutral red. Lactose fermenters form pink to red colonies, while non-fermenters form colourless colonies. 44. Describe the definition for facultative anaerobic bacteria!
They are able to grow and metabolize both in the presence and in the absence of oxygen. In aerobic conditions they perform respiration, in anaerobic condition, they perform fermentation.

46. What is the difference between prevalence and incidence of an infectious disease?
It can be differentiated in chronic diseases. Prevalence: total number of diseases (per 100,000 people). Incidence: number of new cases in a year (per 100,000 people).
47. What is the difference between mortality and lethality of a disease?
Mortality: total number of deaths caused by the disease in a population (usually 100,000 people). Lethality: rate of death (in percent) among patients suffering from the disease.

49. Describe the principle of the Kirby-Bauer (disk diffusion) method used to determine
antibiotic sensitivity! Disks impregnated with different antibiotics are placed on the surface of appropriate agar media that has been inoculated with the bacterium isolated from the patient. After overnight incubation, the antibiotics diffusing from the discs may cause zones of inhibition around the discs. The size of the zone should be compared to standards to determine antibiotic sensitivity. 50. Explain the purpose for using beta-lactamase inhibitors in antibacterial therapy!
Combination of beta-lactamase inhibitors (such as clavulanic acid or sulbactam) with beta-lactamase sensitive penicillins (such as amoxicillin or ampicillin) can overcome resistance mediated by many but not all beta-lactamases. 51. What are the main advantages and disadvantages of live attenuated vaccines as
Advantages: induce not only serum antibodies but also cellular immunity and local IgA
antibodies. Some may be applied orally. Usually fewer doses are needed. Disadvantages: Attenuated strains may revert to virulent in rare cases. They may cause disease in immunosuppressed patients. Live attenuated microbes are usually heat sensitive and must be refrigerated.

57. Regarding the joint effects of 2 antibiotics, what does synergism mean? The effect of the two drugs together is significantly higher than the sum of the effects of the two drugs acting separately. 58. Regarding the joint effects of 2 antibiotics, what does antagonism mean? The effect of the two drugs together is significantly lower than the effect of the more effective drug alone. Selective inhibition of the growth of the microorganism without damage to the host.In other words: the drug is highly toxic to the bacteria, but not toxic (or have very low toxicity) to the human host.
60. How can one identify the different surface antigens of Gram negative bacteria?
with slide agglutination tests using antibodies of known specificity
61. What is the mechanism of action of diphtheria toxin?
Inhibition of protein synthesis in eukaryotic cells by ADP-ribosylation of ribosomal EF-2 (elongation factor-2)
62. What is the mechanism of action of tetanus toxin?
It causes spastic paralysis by blocking the release of inhibitory neurotransmitters(glycine) in synapses
63. What roles can be attributed to specific antibodies in antibacterial immunity? Specify at
least 3! a. neutralisation of exotoxins and enzymesb. complement-dependent bacteriolysis (Gram-negatives) c. opsonisation (helping phagocytosis) d. interfering with attachment of bacteria to mucosal surfaces
64. Starting from a fixed smear, specify the main steps of Gram stain in the appropriate
order! 1. Crystal violet 2. Lugol solution (iodine) 3. Differentiation: ethanol wash 4. Counterstaining: safranin or fuchsin (wash with tap water after each step)
65. Starting from a fixed smear, specify the main steps of the acid-fast stain (Ziehl-Neelsen)
1. Stain with carbol-fuchsin (with heating) 2. Differentiation: wash with acid-ethanol 3. Counterstaining with methylene-blue (wash with tap water after each step)
66. What is the difference between agglutination and precipitation?
Both are serological reactions where specific binding of the antigen with the antibody directly results in a reaction visible by the naked eye. The difference is in the nature of the antigen. Agglutination: particulate antigen (RBC, bacteria, latex particles). Precipitation: antigen is in solution before the reaction.
67. What does titer mean in serological tests?
The highest dilution of the serum sample that gives a positive reaction in the test.
68. How can one differentiate between past and current infections in serological tests?
Current infections are indicated by: either IgM class specific antibodies or, in the case of paired serum specimens (taken from the same patient at least 7-10 days apart), a significant (at least 4-fold) rise in the titer of specific antibodies.
Specify the main steps of an ELISA test in which we detect antibodies from patients’
serum samples using known antigens! 1. Binding antigen to plastic surface (in wells of a 96-well plate) 2. Adding diluted serum sample (specific antibodies bind to the antigen) 3.Adding conjugate (secondary antibody conjugated with an enzyme) 4. Adding the substrate of the enzyme, reading the colour reaction.
70. How can one determine the minimal inhibitory concentration of an antibiotic to a
bacterial isolate? Inoculate the bacterial isolate into a series of test tubes containing 2-fold dilution series of the drug. After overnight incubation, the lowest concentration of drug that prevents visible growth of the organism is the MIC.
___________________________________________________________________________ CLINICAL BACTERIOLOGY 1.
Mention 5 diseases that can be caused by Staphylococcus aureus!
Impetigo, furunculus, pneumonia, osteomyelitis, food poisoning etc.
Mention 2 toxin-mediated staphylococcal diseases!
toxic shock syndrome (TSS), scalded skin syndrome, food poisoning
Mention 3 toxic products produced by Staphylococcus aureus!
TSST (toxic shock syndrome toxin), enterotoxin, exfoliatin, leukocidins, hemolysins 4. Which is the most virulent species of Staphylococcus? S. aureus
Which enzymatic virulence factor is characteristic exclusively for Staphylococcus
aureus? coagulase
How can we identify the source of infection in a staphylococcal food poisoning?
by phage typing
Which antibacterial drug is the first choice in serious infections caused by methycillin
resistant Staphylococcus aureus (MRSA) strains? glycopeptides (vancomycin, teicoplanin)
In which disease is Staphylococcus saprophyticus considered an obligate pathogen!
cystitis in young women
Which cell constituents determine the group-specific, and the type specific antigens of
Streptococcus pyogenes, respectively? group specific: C- polysaccharide type specific: M protein
Mention 3 enzymes produced by Streptococcus pyogenes that enhance the spread of
the bacterial infection in the body! Streptokinase (fibrinolysin), hyaluronidase, streptodornase (DNAse)
List 3 diseases caused by Streptococcus pyogenes in the skin or in subcutaneous
tissues! impetigo (pyoderma), cellulitis, erysipelas, fasciitis, myositis
Mention a toxin-mediated streptococcal disease, specify the name of the toxin and its
mechanism of action! Scarlet fever - erythrogenic toxin – superantigen causing capillary destruction Glomerulonephritis, rheumatic fever, erythema nodosum, chorea minor.
14. Which product of Streptococcus pyogenes has a major pathogenic role in
poststreptococcal diseases? M protein: may induce hypersensitivity reactions
How long does immunity against scarlet fever exist? Which immune effector
mechanism is involved? Life-long immunity. Antitoxic antibodies are involved.
What is the drug of first choice in Streptococcus pyogenes infection?
Penicillin-G
What is the patomechanism of post-streptococcal rheumatic fever?
type II hypersensitivity (cytotoxic antibodies)
What is the patomechanism of post-streptococcal glomerulonephritis?
type III hypersensitivity (immune complexes)
Which Streptococcus species plays major role in the meningitis of newborn babies?
Group B Streptococcus (S. agalactiae)
What is (are) the major causative agent(s) for subacute bacterial endocarditis?
Viridans streptococci
What are the characteristics of Enterococci that can be used in their identification?
D group polysaccharide antigen; tolerance to bile and hydrolysis of esculin (BEA medium: bile esculin agar); growth in the presence of 6,5 % NaCl
What are the specific morphologic features of Streptococcus pneumoniae?
Gram positive diplococcus, lancet shape, capsule.
Mention 3 diseases that can be caused by Streptococcus pneumoniae!
Pneumonia, meningitis, sinusitis, otitis media, sepsis, (ulcus serpens corneae)
What fast diagnostic procedure can be used in acute Neisseria gonorrhoeae infection?
Demonstration of bacteria (intracellular in PMNs) from urethral discharge by Gram or methylene blue stain; PCR amplification of bacterial DNA
What kind of immunity develops after Neisseria gonorrhoeae infection?
Partial immunity of short duration; no protection from reinfection
Specify at least 2 of the most important manifestations of disseminated gonorrhoeal
infections! arthritis, skin eruptions, (endocarditis, meningitis)
What is the major manifestation of Neisseria gonorrhoeae infection in newborns?
How can it be prevented? Blenorrhoea (ophtalmia) neonatorum, silver acetate eye drops or erythromycin ointment
Mention at least 3 major virulence factors of Neisseria gonorrhoeae!
pilus, outer membrane proteins, LOS (lipooligosaccharide), IgA protease
Mention at least 2 major virulence factors of Neisseria meningitidis!
polysaccharide capsule, LPS, IgA protease
What is the site of entry of Neisseria meningitidis infection? What diseases are caused
by this bacterium? The site of entry is the nasopharynx (transmitted by airborne droplets). Meningococcemia (characterized by skin lesions), and acute (purulent) bacterial meningitis.
What kinds of prophylactic measurements are available against Neisseria meningitidis
infections? Chemoprophylaxis: rifampin or ciprofloxacin. Vaccination: capsular polysaccharide (types A, C, Y and W135). No vaccine against type B!
Which rapid diagnostic methods can be used in the presumptive diagnosis of purulent
bacterial meningitis? Gram or methylene blue stain of CSF sediment Demonstration of bacterial capsular antigens by latex agglutination (from CSF)
Which capsular serotype is included in the vaccine against Haemophilus influenzae?
34. Which are the portals of entry of Bacillus anthracis?
Skin, lungs, gastrointestinal tract
Mention 3 important bacteria involved in nosocomial (hospital-acquired) infections!
Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli
Mention four E. coli pathogenetic groups involved in enteric diseases!
Enteropathogenic E. coli (EPEC) Enterotoxic E. coli (ETEC) Enteroinvasive E. coli (EIEC) Enterohemorrhagic E. coli (EHEC) Enteroaggregative E. coli (EAggEC)
What are the most important extraintestinal infections caused by E. coli? Mention at
least 3 of them! urinary tract infections, neonatal meningitis, nosocomial wound infections
38. The most frequent causative agent of urinary tract infections is:Escherichia coli
Which 2 diseases are caused by E. coli O157:H7?
hemorrhagic colitis +/- HUS (hemolytic uraemic syndrome)
What is the reservoir of Salmonella typhi?
humans (with disease, or healthy carriers)
41. Which bacteria cause most frequently typhoid fever and enteric fever, respectively?
Salmonella typhi (typhoid) Salmonella paratyphi A, B, C (enteric fever) 42. When typhoid fever is suspected, what kinds of clinical samples should be used to isolate
the causative agent in the first 2 weeks of the disease? Blood, (bone marrow)
43. What is the route of infection in Salmonella gastroenteritis?
Ingestion of contaminated food (such as eggs, cream, mayonnaise, creamed foods, etc.) containing a sufficient number of Salmonella. 44. Which antibacterial drugs should be administered in gastroenteritis caused by
Salmonella? Antibiotics are not usually necessary unless the infection is generalised. In case of extraintestinal infection (very young, very old or immunosuppressed patients): ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or ciprofloxacin. 45. List the 4 Shigella species causing human disease! Shigella dysenteriae, S. flexneri, S. boydii, S. sonnei
46. Mention 2 bacterial species belonging to different genera that cause bacillary dysentery
Shigella dysenteriae, (Shigella flexneri, Shigella boydii, Shigella sonnei), enteroinvasive E. coli (EIEC)47. Mention 3 bacterial species belonging to different genera that cause enteritis or
enterocolitis! Campylobacter jejuni, Escherichia coli, Salmonella enteritidis, Shigella, Yersinia enterocolitica
Mention 2 bacteria causing intestinal infections which have animal reservoirs!
Salmonella (not Typhi and Paratyphi!), Campylobacter jejuni, Yersinia enterocolitica, Listeria monocytogenes, E. coli O157
49. What are the modes of transmission for the 2 different epidemiologic forms of plague?
- Bubonic plague is transmitted by the bite of infected rat fleas from rats to humans. - Primary pneumonic plague spreads directly from human to human via respiratory droplets.
What are the possible portals of entry of Francisella tularensis? Specify at least 4!
tick bite, mucous membranes, skin abrasions, resp. tract, gastroint. tract
51. How do humans acquire brucellosis? Where do the bacteria replicate in the human body?
Via contaminated milk products or through skin abrasions (contact with animals). Organisms spread to the mononuclear phagocytes of the reticuloendothelial system (lymph nodes, liver, spleen, bone marrow).
What are the reservoirs of the different Brucella species, respectively?
B. abortus: cattle B. melitensis: goat, sheep B. suis: swine
53. What is the mechanism of action of cholera toxin?
Cholera toxin activates the adenylate cyclase enzyme in cells of the intestinal mucosa leading to increased levels of intracellular cAMP, and the secretion of large amount of water, Na+, K+, Cl-, and HCO -3 into the lumen of the small intestine.
54. What is the principle of the treatment for cholera?
Rapid intravenous or oral replacement of the lost fluid and ions. (Administration of isotonic maintenance solution should continue until the diarrhea ceases.) In severe cases: administration of tetracycline (in addition to rehydration).
55. Mention 4 diseases caused by Haemophilus influenzae!
purulent meningitis epiglottitis (obstructive laryngitis) otitis media and sinusitis pneumonia (cellulitis, arthritis)
56. Which disease is caused by Haemophilus ducreyi?
Chancroid (soft chancre or ulcus molle)
57. What can serve as source of infections caused by Pseudomonas aeruginosa?
Pseudomonas species are normally present in the environment and can be isolated from the skin, throat, and stool of some healthy persons. They often colonize hospital food, sinks, taps, mops, and respiratory equipment.
58. Mention 4 diseases that are frequently caused by Pseudomonas aeruginosa!
urinary tract infections wound infections (burns) pneumonia, sepsis (immunosupression) otitis externa
Mention at least 3 drugs which may be effective to treat infections caused by
Pseudomonas aeruginosa! certain penicillins: piperacillin/tazobactam combinationa 3rd generation cephalosporin: ceftazidim a 4th generation cephalosporin: cefepimecertain aminoglycosides: gentamycin, tobramycin, amikacin carbapenems: imipenem, meropenem
60. Which 2 diseases are caused by Legionella pneumophila?
- legionellosis, legionnairs’ disease (atypical pneumonia) - Pontiac fever (mild, flu like illness without pneumonia)
61. List 3 important virulence factors of Bordetella pertussis!
filamentous hemagglutinin, pertussis toxin, adenylate-cyclase toxin, tracheal cytotoxin
62. Mention 3 bacterium species causing food poisoning!
Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Clostridium botulinum, Vibrio parahaemolyticus, (Salmonella serotypes causing enterocolitis)
63. Which bacterium has the highest germ number in the colon?
Bacteroides fragilis
64. Mention 4 bacterial genera that are obligate anaerobes!
Clostridium, Bacteroides, Prevotella, Porphyromonas, Fusobacterium, Actinomyces, Bifidobacterium, Peptostreptococcus, Propionibacterium
65. Which is the most important gas gangrene Clostridium? What is its main virulence factor?
Clostridium perfringens alpha-toxin (lecithinase)
66. Mention 3 Clostridium species causing gas gangrene! How are they acquired?
Clostridium perfringens, C. novyi, C. septicum, C. histolyticum, C. tertium, C. bifermentans, C. sporogenes The site of infection is usually a wound that comes into contact with Clostridium spores that germinate in an anaerobic environment. 67. How can be tetanus prevented in patients who have wounds possibly contaminated with C. tetani spores? Wound should be cleaned and debrided; tetanus toxoid booster injection given; tetanus immunoglobulin (TETIG) in previously unvaccinated patients and in case of heavy contamination of wound; penicillin may be added prophylactically68. What are the main symptoms of tetanus infection? Specify at least 3!
Spastic paralysis: muscle spasms; lockjaw(trismus), rhisus sardonicus (grimace of the face), opisthotonus (spasm of the back); respiratory paralysis
69. What is the mechanism of action of the botulinus toxin?
Blocks release of acetylcholine in peripheral nerve synapses; flaccid paralysis: diplopia (double vision), dysphagia (difficulty to swallow), dysphonia (hoarseness), respiratory paralysis.
71. What kind of therapy is used to treat botulism?
Treatment: respiratory support + trivalent antitoxin
72. Explain whether or not antibiotic treatment is useful in botulism!
Not, because antibiotics are not effective against preformed toxins.
73. What diseases may be associated with Helicobacter pylori? Specify at least 3!
Gastritis, peptic and duodenal ulcers, gastric carcinoma, MALT lymphoma74. What is the most important virulence factor of Corynebacterium diphtheriae?
Diphtheria toxin
75. What is the mechanism of action of the diphtheria toxin?
Inhibits protein synthesis. Inhibits peptide elongation in eukaryotic ribosomes by ADP ribosylation of EF-2 (elongation factor-2)
76. How long does immunity against diphtheria exist? Which immune effector mechanism is
involved? Antitoxic antibodies, long lasting immunity
77. Which assays should be done in the lab in order to prove diphtheria?
Smears of the throat swab should be stained with methylene blue or Neisser stain; bacteria are cultured on Löffler’s or tellurite (Clauberg) medium; toxin productionmust be demonstrated by agar precipitation ( ELEK-test)
78. What feature of Mycobacteria make them acid fast?
The cell envelope contains a high amount (60 – 70 %) of complex lipids: mycolic acid, cord factor. Once the cells are stained (by carbol-fuchsin) they resist decolorisation by acid-ethanol. 79. Mention 2 atypical Mycobacterium species!
M. kansasii, M. marinum, M. avium-intracellulare complex, M. fortuitum-chelonei complex

80. How can one demonstrate the presence of Mycobacterium tuberculosis in clinical
samples? Acid-fast staining (Ziehl-Neelsen) Culture on selective media (Löwenstein-Jensen agar, liquid BACTEC medium) PCR amplification of bacterial DNA
81. Why is multi-drug therapy used for tuberculosis?
To prevent the overgrowth of drug-resistant mutants during the long treatment period (if bacteria resistant to one drug emerge, they are most probably inhibited by the other drugs). 82. What is the main immune defense mechanism against Mycobacterium tuberculosis?
activated macrophages
83. Mention 3 antituberculotic drugs that are of first choice against Mycobacterium
tuberculosis! isoniazid (INH), pyrazinamid, rifampin, (ethambutol, streptomycin)
What disease is caused by Mycobacterium avium-intracellulare? What patients are
characteristically susceptible to infection? It causes TB, especially in immunosuppressed patients (such as AIDS patients).
What is the reservoir of Mycobacterium tuberculosis?
What is the reservoir of atypical Mycobacteria?
environment (soil, water)87. What are the 2 distinct forms of leprosy?
Tuberculoid, lepromatous forms88. Mention 3 Gram-negative bacteria belonging to different genera causing zoonosis!
Brucella, Francisella tularensis, Yersinia pestis, Pasteurella 89. Mention 2 Gram-positive bacteria belonging to different genera causing zoonosis!
Listeria monocytogenes, Bacillus anthracis, Erysipelothrix rhusiopathiae
90. Mention 3 bacterial species belonging to different genera that are frequent causes of
urinary tract infections! E. coli, Klebsiella, Proteus, Pseudomonas aeruginosa, Enterococcus faecalis
91. Mention one aerobic and one anaerobic bacterium of the normal flora of the skin!
aerobic: Staphylococcus epidermidis anaerobic: Propionobacterium acnes
Give two genuses for each category of bacteria!
Gram positive aerobic: Staphylococcus, Streptococcus, Bacillus, Corynebacterium,… Gram positive anaerobic: Clostridium, Actinomyces, Propionibacterium, Lactobacillus
Give two genuses for each category of bacteria!
Gram negativ aerobic: Vibrio, Neisseria, Haemophilus… Gram negativ anaerobic: Bacteroides, Prevotella, Porphyromonas, Veillonella…
Give 2 genuses for each category of bacteria!
Gram positive coccus: Staphylococcus, Streptococcus Gram negative coccus: Neisseria, Veillonella Gram positive rod: Clostridium, Bacillus
Give 2 genuses for each category of bacteria!
Gram negative rod: E. coli, Salmonella, Shigella Spirochetes: Treponema, Borrelia, Leptospira
Describe the color and the shape of Clostridia in a Gram stained smear of gas
gangrene exudate! Gram positive (dark blue) rod(it usually does not form spores in vivo)
Mention 2 antibiotics which can be used in the empirical treatment against Gram
negative obligate anaerobic bacteria! Metronidazol, amoxicillin + clavulanic acid, imipenem
Which 3 bacterial species are the most important causative agents of neonatal (< 1
month of age) meningitis? Streptococcus agalactiae, E. coli, Listeria monocytogenes
Which 3 bacterial species are the most important causative agents of meningitis
among babies (> 1 month of age) and children? Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae
What is the causative agent of febris undulans (undulant fever)?
Brucellae
What is the precise definition of bacterial food poisoning?
Acute disease, usually with vomiting and diarrhea, caused by preformed toxins produced by bacteria contaminating the food. The period between consumption of food and the appearance of symptoms is short (< 4-6 hours).
What are the main symptoms in the different stages of syphilis?
Primary syphilis: nontender ulcer (hard chancre) Secondary lesions: maculopapular rash on skin, and condylomata lata on mucous membranes Tertiary stage: granulomas (gummas), central nervous system involvement (tabes dorsalis, paralysis progressiva), cardiovascular lesions (aortitis, aorta aneurysm)
When syphilis is diagnosed in the lab, which antigens are used in the non-treponemal
and in the specific treponemal antibody tests, respectively? Non-treponemal antibody tests: cardiolipinSpecific treponemal antibody tests: Treponema pallidum
Which are the two different kinds of antibodies which may indicate syphilis? Give
examples for tests demonstrating them!: Reagin (nonspecific antibody) – RPR, VDRL (flocculation tests) Immobilisin (specific antibody) – TPHA (T. pallidum hemagglutination), FTA-ABS (fluorescent treponemal assay – with antibody absorption), TPI (T. pallidum immobilisation test),
What is the advantage and disadvantage of the FTA-ABS syphilis serologic test
compared to the VDRL test?Specific (treponemal) tests such as FTA-ABS are more specific, but they can not be used to follow the efficacy of treatment (because the specific antibodies persist even after effective eradication of bacteria)
What is the drug of first choice in the treatment of syphilis?
penicillin G
What is the reservoir and what is the vector for Borrelia recurrentis?
Reservoir: human; vector: louse
What is used for the laboratory diagnosis of relapsing fever?
Direct demonstration of bacteria from peripheral blood smear by microscopy (Giemsastain or dark field illumination)
What is the first characteristic symptom of Lyme disease? What is the causative
agent? Erythema (chronicum) migrans. Borrelia burgdorferi.
Mention 2 antibacterial drugs that are of first choice in early stage Lyme disease?
Tetracyclines, amoxicillin, cefuroxim
Which symptoms are characteristic for the early and the late phases of disease by
Borrelia burgdorferi? Early: erythema chronicum migrans Late: arthritis, cardiac (myocarditis, pericarditis) and neurological involvement (meningitis, peripheral neuropathies)
What is the reservoir of Leptospira interrogans?
rodents, household animals (dog, swine etc.)
Mention 2 obligate intracellular bacterial genuses!
Rickettsia, Chlamydia, (Coxiella, Ehrlichia)
Mention 4 bacteria causing atypical pneumonia!
Chlamydia pneumoniae Chlamydia psittaci Coxiella burnetii Mycoplasma pneumoniae Legionella pneumophila
What diseases are caused by Rickettsia prowazekii?
Louse-borne epidemic typhus Recurrent form: Brill-Zinsser disease
Mention an antibacterial drug active against rickettsial infections!
Tetracycline, chloramphenicol
What are the reservoir and vector of Rickettsia prowazekii infections?
reservoir: human; vector: louse
What are the reservoir and vector of Rickettsia typhi infections?
reservoir: rodents; vector: flea
What is the causative agent of epidemic typhus?
Rickettsia prowazekii
How can be Chlamydiae and Rickettsiae cultivated?
These are obligate intracellular bacteria, can be cultured in experimental animals, embryonated eggs, and cell culture
Mention an antibacterial drug active against chlamydial infections!
Tetracycline, erythromycin, azithromycin

The same species is capable of existing in two morphological forms (yeast or mold), depending upon enviromental conditions (temperature, nutrients).
Which are the 4 fungal species causing systemic infections?
Coccidioides immitis, Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidioides brasiliensis
Mention 3 species causing opportunistic fungal infections!
Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Mucor spp., Rhizopus spp.
Mention 3 diseases caused by dermatophytons!
Tinea corporis, tinea capitis, onychomycosis, tinea barbae
Mention 3 fungal genera belonging to the dermatophytons!
Trichophyton, Microsporum, Epidermophyton
What is the route of transmission of Sporothrix schenkii?
Traumatically introduced into the skin.
Mention a Candida infection associated with mucosal surfaces!
Soor, vulvovaginitis
Which species is the most important causative agent of fungal meningitis?
Cryptococcus neoformans
Mention 3 manifestations of Candida albicans infections that are characteristic in
AIDS patients? generalised oral candidiasis (GOC), oesophagitis, endocarditis
What are the different forms of pulmonary aspergillosis?
1. Aspergillus ball (in preformed cavities) 2. invasive aspergillosis (in immunosuppression) 3. allergic bronchopulmonary aspergillosis
What is the usual source of infection in systemic mycoses?
What is the usual site of entry of fungi causing systemic mycoses?
respiratory tract (inhalation)
Which morphological form of Coccidioides immitis can be found in the human body?
spherule
Which human pathogenic fungus has a capsule?
Cryptococcus neoformans

________________________________________________________________________ PARASITOLOGY 1.
Mention a worm species for which ab ano ad os auto-reinfection is characteristic in
childhood! Enterobius vermicularis
Mention 2 worm species that migrate through the human lungs in the larval stage!
Ascaris lumbricoides Ancylostoma duodenale Necator americanus Strongyloides stercoralis
Which 2 protozoa may infect the human foetus transplacentally?
Toxoplasma gondii Plasmodium species
What is the laboratory diagnosis of malaria?
Giemsa-stained blood smears. Thick smear is used to screen for the agent, thin smear is used to identify the species.
How long is the erytrocytic cycle of Plasmodium vivax and P. ovale?
How long is the erytrocytic cycle of Plasmodium malariae?
What is the causative agent of malignant malaria?
Plasmodium falciparum
Mention an antimalarial drug active against hypnozoites!
Primaquin
How can one diagnose the African sleeping sickness disease?
Giemsa-stained blood smears are used for direct demonstration Serology may be helpful

Frequently Asked Questions about PL 57 and Management of Severe Allergies in NJ Schools What is a food allergy? A food allergy is an abnormal response to a food, triggered by the body’s immune system. Once the immune system decides that a particular food is harmful, it creates specific antibodies against it. An allergic reaction to food may cause serious illness and, in some